Flowers, teddy bears and victims’ photos began to appear in Copley Square soon after one of two bombs exploded here on April 15, 2013, during the Boston Marathon. In the next couple of weeks, the display grew into this huge memorial for the three who died and the 250 injured. It was a very somber experience to see the names and faces of so many people that were attacked that day and watch as family and friends kept adding their own silent tributes.